1. Field of the Invention
The present invention relates to a mobile communication terminal which is set to a communicable state by mounting a detachable IC card and, a communication start method of the same.
2. Description of the Related Art
In recent years, there is an increasing demand for mobile radio communication apparatuses, namely terminal apparatuses such as a portable telephone and a car telephone, along with needs for personal communication. Also, there are various mobile radio communication systems such as an analog cellular system, a digital cellular system and a cordless telephone system. Especially, the GSM (Global System for Mobile communications) system is one of the digital cellular systems and a pan-European standard.
Such a mobile radio communication terminal used for the GSM system is composed of a mobile radio communication terminal main unit, an SIM (Subscriber Identity Module) card, and a battery pack. The SIM card stores data about a terminal user. This data includes a subscriber number (IMSI: International Mobile Subscriber Identify), an identification number (PIN: Personal Identification Number), a service status code, and abbreviated telephone numbers entered by a subscriber. The battery pack supplies power required for the operation of the mobile radio communication terminal. The mobile radio communication terminal main unit contains an antenna, a keyboard, a display unit, and a control section for controlling transmission and reception of signals. Also, the mobile radio communication terminal contains a storage section for temporarily storing the terminal user data stored in the SIM card. The information stored in the storage section is held while the mobile radio communication terminal main unit is supplied with the power from the battery pack. When no power is supplied from the battery pack, the mobile radio communication terminal main unit cannot hold the terminal user data.
An operation of the mobile radio communication terminal to start access to a network in the GSM system will be described below.
First, the mobile radio communication terminal main unit with the SIM card attached is turned on. Then, the mobile radio communication terminal main unit checks whether the attached SIM card belongs to the terminal user. In the checking operation, the identification number entered from a keyboard by the terminal user is compared with the PIN number stored in the SIM card. When the entered identification number is coincident with the PIN number, it is confirmed that the SIM card attached to the mobile radio communication terminal main unit belongs the terminal user. The mobile radio communication terminal main unit stores in the storage section, the terminal user data which has been stored in the SIM card. After completing the above-mentioned operation, the mobile radio communication terminal main unit is set to an accessible state to the network. Once the mobile radio communication terminal main unit is made accessible to the network, the access to the network is permitted through only the operation for power on as long as the data stored in the storage section is not deleted.
The storage section can hold the terminal user data unless the battery pack is detached from the mobile radio communication terminal main unit. On contrast, even if the battery pack is temporarily detached, the mobile radio communication terminal main unit prompts a terminal user to enter the identification number for confirming that the attached SIM card belongs to the terminal user.
A mobile communication terminal usable in the GSM system is demanded in which communication is possible without requesting a terminal user to enter the identification number even when the battery pack is detached from the mobile radio communication terminal main unit.
In conjunction with the above description, a portable phone is disclosed in Japanese Laid Open Patent Application (JP-A-Heisei 9-27839). In this reference, when an IC card (2) with charge is attached to a portable phone main unit (1), charge is removed by electrostatic brush (3). Also, an attachment switch (4) and a detachment switch (5) forcibly switch off the power of the portable phone main unit when the IC card is attached or detached. Thus, the attaching or detaching operation of the IC card is carried out in the power off state of the portable phone main unit so that destruction of data and any erroneous operation are prevented.
Also, a mobile phone is disclosed in Japanese Laid Open Patent Application (JP-A-Heisei 9-84101). In this reference, when the mobile phone (1) with a SIM card (2) is used, SIM data is read out from the SIM card (2), and transferred to a memory (47) in the mobile phone and stored therein. The SIM data added or updated during a communicating operation are transferred to a SIM memory (8) and stored therein when the communication is ended. The communication with the SIM card (2) and the storing operation in the SIM memory (8) are carried out by a SUB-CPU (30) which is backed up by a power supply (34) different from a main power supply (3). Even if the operation of a main processor (9) in the mobile phone is stopped because of the voltage change of the main power supply (3), or the careless power off during use of the mobile phone, the SIM data having been stored in the memory (47) can be normally stored in the SIM memory (8).
An object of the present invention is to provide a mobile communication terminal which can communicate in the state in which an IC card is attached.
Another object of the present invention is to provide a mobile communication terminal which can be connected with a network without identifying an owner of the attached IC card even when the battery pack is temporarily removed from the terminal.
Still another object of the present invention is to provide a mobile communication terminal which can be used in the GSM system.
Yet still another object of the present invention is to provide a mobile communication terminal which can be connected with a network without entering an identification number even when the battery pack is temporarily removed from the terminal.
In an aspect of the present invention, a mobile communication terminal includes an IC card, a power supply, and a control section. The IC card stores an identification number. The power supply supplies power to the mobile communication terminal. The control section can set the mobile communication terminal to a communication possible state when the power is supplied from the power supply and an entered identification number is coincident with the identification number stored in the IC card. Also, the control section can set the mobile communication terminal to the communication possible state depending on a power down time period without an entering operation of the identification number when the supply of the power to the mobile communication terminal is stopped and then recovered.
In this case, while the power is supplied from the power supply, the control section reads out the identification number from the IC card. The mobile communication terminal may further include a storage section and an encrypting section. The encrypting section encrypts the read out identification number using a random number, stores the encrypted identification number in the storage section, and holds the random number.
In this case, the mobile communication terminal may further include a detecting section, and a measuring section. The detecting section detects the power down of the power supplied from the power supply to generate a power down signal, and detects recovery of the power supplied from the power supply to generate a power recovery signal. The measuring section starts counting of the power down time period in response to the power down signal and stops the counting of the power down time period. In this case, the control section reads out the encrypted identification number from the storage section, decrypts the encrypted identification number using the random number held in the encrypting section, when the counted power down time period between the power down and the power recovery is shorter than a predetermined time period. Thus, the control section sets the mobile communication terminal to the communication possible state when the decrypted identification number is coincident with the identification number stored in the IC card.
In this case, the measuring section may delete the random number held in the encrypting section, when the counted power down time period after the power down is equal to or longer than the predetermined time period.
Also, the mobile communication terminal may further include a backup power supply. The storage section and the encrypting section are operable based on power supplied from the backup power supply when the supply of the power from the power supply is down.
Instead, the storage section, the encrypting section, the detecting section and the measuring section are operable based on power supplied from the backup power supply when the supply of the power from the power supply is down.
Also, the IC card may be composed of a SIM card.
In another aspect of the present invention, a method of setting a mobile communication terminal to a communication possible state, is attained by (a) supplying power from a power supply; by (b) entering an identification number from an operation unit; by (c) comparing the entered identification number with an identification number stored in an IC card; by (d) setting the mobile communication terminal to the communication possible state when the power is supplied from the power supply and an entered identification number is coincident with the identification number stored in the IC card; and by (e) setting the mobile communication terminal to the communication possible state depending on a power down time period without the (b) entering step when the supply of the power from the power supply is downed and then recovered.
In this case, the (d) setting step may be attained by (f) reading out the identification number from the IC card while the power is supplied from the power supply; by (g) encrypting the read out identification number using a random number; by (h) storing the encrypted identification number in a storage section; and by (i) holding the random number.
Also, the (e) setting step may be attained by detecting the power down of the power supplied from the power supply to generate a power down signal; by detecting the recovery of the power supplied from the power supply to generate a power recovery signal; by counting of the power down time period in response to the power down signal and stops the counting of the power down time period; by reading out the encrypted identification number from the storage section; by decrypting the encrypted identification number using the random number held in the encrypting section, when the counted power down time period between the power down and the power recovery is shorter than a predetermined time period; and by setting the mobile communication terminal to the communication possible state when the decrypted identification number is coincident with the identification number stored in the IC card.
Also, the (e) setting step may further include deleting the random number held in the encrypting section, when the counted power down time period after the power down is equal to or longer than the predetermined time period.
Also, the IC card may be composed of a SIM card.